/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.runtime.rest.handler.job.checkpoints;

import org.apache.flink.api.common.time.Time;
import org.apache.flink.runtime.checkpoint.AbstractCheckpointStats;
import org.apache.flink.runtime.checkpoint.CheckpointStatsCounts;
import org.apache.flink.runtime.checkpoint.CheckpointStatsHistory;
import org.apache.flink.runtime.checkpoint.CheckpointStatsSnapshot;
import org.apache.flink.runtime.checkpoint.CompletedCheckpointStatsSummary;
import org.apache.flink.runtime.checkpoint.RestoredCheckpointStats;
import org.apache.flink.runtime.executiongraph.AccessExecutionGraph;
import org.apache.flink.runtime.rest.handler.HandlerRequest;
import org.apache.flink.runtime.rest.handler.RestHandlerException;
import org.apache.flink.runtime.rest.handler.job.AbstractExecutionGraphHandler;
import org.apache.flink.runtime.rest.handler.legacy.ExecutionGraphCache;
import org.apache.flink.runtime.rest.messages.EmptyRequestBody;
import org.apache.flink.runtime.rest.messages.ErrorResponseBody;
import org.apache.flink.runtime.rest.messages.JobIDPathParameter;
import org.apache.flink.runtime.rest.messages.JobMessageParameters;
import org.apache.flink.runtime.rest.messages.MessageHeaders;
import org.apache.flink.runtime.rest.messages.ResponseBody;
import org.apache.flink.runtime.rest.messages.checkpoints.CheckpointStatistics;
import org.apache.flink.runtime.rest.messages.checkpoints.CheckpointingStatistics;
import org.apache.flink.runtime.rest.messages.checkpoints.MinMaxAvgStatistics;
import org.apache.flink.runtime.webmonitor.RestfulGateway;
import org.apache.flink.runtime.webmonitor.history.ArchivedJson;
import org.apache.flink.runtime.webmonitor.history.JsonArchivist;
import org.apache.flink.runtime.webmonitor.retriever.GatewayRetriever;

import org.apache.flink.shaded.netty4.io.netty.handler.codec.http.HttpResponseStatus;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.Executor;

/**
 * Handler which serves the checkpoint statistics.
 */
public class CheckpointingStatisticsHandler extends AbstractExecutionGraphHandler<CheckpointingStatistics, JobMessageParameters> implements JsonArchivist {

	public CheckpointingStatisticsHandler(
			GatewayRetriever<? extends RestfulGateway> leaderRetriever,
			Time timeout,
			Map<String, String> responseHeaders,
			MessageHeaders<EmptyRequestBody, CheckpointingStatistics, JobMessageParameters> messageHeaders,
			ExecutionGraphCache executionGraphCache,
			Executor executor) {
		super(leaderRetriever, timeout, responseHeaders, messageHeaders, executionGraphCache, executor);
	}

	@Override
	protected CheckpointingStatistics handleRequest(HandlerRequest<EmptyRequestBody, JobMessageParameters> request, AccessExecutionGraph executionGraph) throws RestHandlerException {
		return createCheckpointingStatistics(executionGraph);
	}

	@Override
	public Collection<ArchivedJson> archiveJsonWithPath(AccessExecutionGraph graph) throws IOException {
		ResponseBody json;
		try {
			json = createCheckpointingStatistics(graph);
		} catch (RestHandlerException rhe) {
			json = new ErrorResponseBody(rhe.getMessage());
		}
		String path = getMessageHeaders().getTargetRestEndpointURL()
			.replace(':' + JobIDPathParameter.KEY, graph.getJobID().toString());
		return Collections.singletonList(new ArchivedJson(path, json));
	}

	private static CheckpointingStatistics createCheckpointingStatistics(AccessExecutionGraph executionGraph) throws RestHandlerException {
		final CheckpointStatsSnapshot checkpointStatsSnapshot = executionGraph.getCheckpointStatsSnapshot();

		if (checkpointStatsSnapshot == null) {
			throw new RestHandlerException("Checkpointing has not been enabled.", HttpResponseStatus.NOT_FOUND);
		} else {
			final CheckpointStatsCounts checkpointStatsCounts = checkpointStatsSnapshot.getCounts();

			final CheckpointingStatistics.Counts counts = new CheckpointingStatistics.Counts(
				checkpointStatsCounts.getNumberOfRestoredCheckpoints(),
				checkpointStatsCounts.getTotalNumberOfCheckpoints(),
				checkpointStatsCounts.getNumberOfInProgressCheckpoints(),
				checkpointStatsCounts.getNumberOfCompletedCheckpoints(),
				checkpointStatsCounts.getNumberOfFailedCheckpoints());

			final CompletedCheckpointStatsSummary checkpointStatsSummary = checkpointStatsSnapshot.getSummaryStats();

			final CheckpointingStatistics.Summary summary = new CheckpointingStatistics.Summary(
				MinMaxAvgStatistics.valueOf(checkpointStatsSummary.getStateSizeStats()),
				MinMaxAvgStatistics.valueOf(checkpointStatsSummary.getEndToEndDurationStats()),
				MinMaxAvgStatistics.valueOf(checkpointStatsSummary.getAlignmentBufferedStats()));

			final CheckpointStatsHistory checkpointStatsHistory = checkpointStatsSnapshot.getHistory();

			final CheckpointStatistics.CompletedCheckpointStatistics completed = checkpointStatsHistory.getLatestCompletedCheckpoint() != null ?
				(CheckpointStatistics.CompletedCheckpointStatistics) CheckpointStatistics.generateCheckpointStatistics(
					checkpointStatsHistory.getLatestCompletedCheckpoint(),
					false) :
				null;

			final CheckpointStatistics.CompletedCheckpointStatistics savepoint = checkpointStatsHistory.getLatestSavepoint() != null ?
				(CheckpointStatistics.CompletedCheckpointStatistics) CheckpointStatistics.generateCheckpointStatistics(
					checkpointStatsHistory.getLatestSavepoint(),
					false) :
				null;

			final CheckpointStatistics.FailedCheckpointStatistics failed = checkpointStatsHistory.getLatestFailedCheckpoint() != null ?
				(CheckpointStatistics.FailedCheckpointStatistics) CheckpointStatistics.generateCheckpointStatistics(
					checkpointStatsHistory.getLatestFailedCheckpoint(),
					false) :
				null;

			final RestoredCheckpointStats restoredCheckpointStats = checkpointStatsSnapshot.getLatestRestoredCheckpoint();

			final CheckpointingStatistics.RestoredCheckpointStatistics restored;

			if (restoredCheckpointStats == null) {
				restored = null;
			} else {
				restored = new CheckpointingStatistics.RestoredCheckpointStatistics(
					restoredCheckpointStats.getCheckpointId(),
					restoredCheckpointStats.getRestoreTimestamp(),
					restoredCheckpointStats.getProperties().isSavepoint(),
					restoredCheckpointStats.getExternalPath());
			}

			final CheckpointingStatistics.LatestCheckpoints latestCheckpoints = new CheckpointingStatistics.LatestCheckpoints(
				completed,
				savepoint,
				failed,
				restored);

			final List<CheckpointStatistics> history = new ArrayList<>(16);

			for (AbstractCheckpointStats abstractCheckpointStats : checkpointStatsSnapshot.getHistory().getCheckpoints()) {
				history.add(CheckpointStatistics.generateCheckpointStatistics(abstractCheckpointStats, false));
			}

			return new CheckpointingStatistics(
				counts,
				summary,
				latestCheckpoints,
				history);
		}
	}
}
